model_id/id = the model unique name of the class you want apply
permission on (Example
model_res_partner)

group_id/id = group permission apply on (yopu can define it in xml
group file or call an existing group
with syntax module.group_id)

perm_read,perm_write,perm_create,perm_unlink
= the 4 values for the relative permission to read,
write,create,unlink record on defined
class. 1 is True (you can do this action) and 0 is Faslse (you can't)

A simple way to understand this file is to read an existing csv in some OpenERP base module like sale, account, product, etc...